adult joke

Dan poked his nose to my computer and tried to understand a joke which I was reading.

Joke : ......this machine provides service men need when away from their wives.....

Dan : What does it mean?

Me : It's an adult joke.

Dan : Oh...adultery!

(Actually it's a vending machine that sews buttons but the silly man opened his fly and got something else sewn.)

Dan : What happened?

Lyn and I : It's an adult joke!!!